drm/msm/hdmi: drop clock frequency assignment

drm/msm/hdmi: drop clock frequency assignment

The only clock which has frequency being set through hpd_freqs is the
"core" aka MDSS_HDMI_CLK clock. It always has the specified frequency,
so we can drop corresponding clk_set_rate() call together with the
hpd_freq infrastructure.

Reviewed-by: Jessica Zhang <quic_jesszhan@quicinc.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/651717/
Link: https://lore.kernel.org/r/20250505-fd-hdmi-hpd-v5-5-48541f76318c@oss.qualcomm.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>